JP6167051B2 - Wind turbine blade, wind turbine rotor and wind power generator - Google Patents

Description

  The present disclosure relates to a wind turbine blade, a wind turbine rotor, and a wind power generator.

  In recent years, wind power generators using wind power have been spreading from the viewpoint of conservation of the global environment. The wind turbine generator converts wind kinetic energy into rotational energy of a wind turbine rotor including wind turbine blades and a hub, and further converts this rotational energy into electric power by a generator.

  In such a wind turbine generator, the wind turbine rotor plays a role of converting wind kinetic energy into rotational energy, and many wind turbine rotors having a configuration in which a plurality of blades are radially attached to a hub are widely used. In order to improve the efficiency (blade efficiency) of the wind turbine rotor as a whole, various airfoil types have been conventionally proposed.

  For example, Patent Document 1 discloses an aerofoil having a maximum blade thickness within a range of 20% to 30% from the leading edge along the cord length. In Patent Document 2, the typical blade thickness ratio in the blade root region is 24%, the typical blade thickness ratio in the blade tip side region is 21%, and the typical blade thickness ratio in the tip region is 16%. The set configuration is described. Patent Document 3 describes an airfoil in which a design lift coefficient is set in a range of 1.10 to 1.25 with a blade thickness ratio in a range of 14% to 45%.

European Patent Application Publication No. 1760310 European Patent Application No. 0675285 European Patent Application No. 1152148

By the way, in recent years, wind power generators have tended to increase in size in order to improve applicability to the low wind speed area market and to increase the capacity for economic improvement. Wind turbine blades are becoming longer. In order to realize a long blade while maintaining the aerodynamic performance of the wind turbine blade, it is conceivable to increase the size of the wind turbine blade while maintaining the similar shape of the wind turbine blade.
However, simply increasing the size of the wind turbine blade significantly increases the weight of the wind turbine blade, decreases the manufacturability of the wind turbine blade (for example, decreases the resin impregnation property to the molding mold), and decreases the transport performance of the wind turbine blade ( There are problems such as the maximum width of the wind turbine blade, that is, the limitation of transportability due to the maximum cord length, and the deterioration of the operability of the wind turbine generator (necessity of preventing interference between the tower nacelle and the blade during blade pitch control). It can happen. These problems become more significant as the maximum cord length of the wind turbine blade increases.
For this reason, it is necessary to impose restrictions on the maximum cord length when realizing a longer wind turbine blade.

  However, in order to achieve optimum aerodynamic performance, it is necessary to bring the cord length close to the optimum size that is inversely proportional to the product of the radial position and the design lift coefficient. For this reason, if a restriction is imposed on the maximum code length as described above, the code length may be insufficient with respect to the optimum value, and aerodynamic performance may be deteriorated.

  Therefore, in view of the trend of longer wind turbine blades in recent years, for example, in the conventional wind turbine blades described in Patent Documents 1 to 3, the design lift coefficient in the blade length direction region near the maximum cord length position is not sufficient. A further increase in the design lift coefficient in this region is desired.

  In view of the above circumstances, at least some embodiments of the present invention provide a wind turbine blade, a wind turbine rotor, and a wind turbine generator that can realize a high design lift coefficient in a blade length direction region near the maximum cord length position. Objective.

A wind turbine blade according to some embodiments of the present invention includes:
A wind turbine blade for a wind turbine rotor having a back surface and an abdominal surface facing each other,
The windmill blade is in a blade length direction region of the windmill blade where a ratio of a radial position r of the windmill rotor to a radius R of the windmill rotor is 0.1 or more and 0.4 or less.
The first dimensionless value y _max represented by the ratio of the maximum back surface thickness y _max that is the maximum value of the distance from the code to the maximum blade thickness t _max that is the maximum value of the distance between the back surface and the abdominal surface. / _{t max} is 0.36 or more 0.46 or less, and, second dimensionless value _y f _{/ y max} represented by the ratio of the back front bulging amount _{y f} with respect to the rear maximum thickness _{y max} 0.62 Is equal to or greater than 0.76 (however, the back front bulge amount y _f is defined as a distance x _max from the front edge to the cord direction position of the cord direction position of the back surface having the maximum back surface thickness y _max. The distance from the front edge is the distance from the cord to the back surface at a cord direction position of 0.3x _max )
It has an airfoil.

As a result of intensive studies by the present inventors, it has been found that the airfoil satisfying the conditions relating to the first dimensionless value and the second dimensionless value described above has a high design lift coefficient. The wind turbine blade is based on such knowledge of the present inventors, and is intended to improve the aerodynamic performance of the wind turbine blade by improving the airfoil shape.
In other words, the airfoil of the wind turbine blade is configured such that the ratio of the maximum back thickness y _max to the maximum blade thickness (first dimensionless value) is set to 0.46 or less to reduce the overall bulge to the back side of the airfoil. In addition, the ratio (second dimensionless value) of the back front bulge amount y _{f to} the back maximum thickness y _max is set to 0.76 or less, and the local (front edge to x _max from the front edge to x _max is set. The bulge to the back side of the shape is suppressed. In this way, the overall bulge on the back surface and the bulge of the local back surface shape on the leading edge side are suppressed, so that the boundary layer along the back surface (thickness in the blade surface normal direction in the region where the flow velocity near the blade surface is slow) ) Is delayed, peeling from the back surface on the trailing edge side (rear edge peeling) is suppressed, and lift can be improved. Thus, the airfoil can achieve a high design lift coefficient.
Furthermore, the airfoil of the wind turbine blade is configured such that the ratio of the maximum back thickness y _max to the maximum blade thickness (first dimensionless value) is set to 0.36 or more so that the overall bulge toward the back side of the airfoil is increased. While securing a certain amount, the ratio (second dimensionless value) of the back front bulge amount y _{f to} the back maximum thickness y _max is set to 0.62 or more, and the airfoil front edge side local (front edge to x _max The bulge to the back side of the shape is secured to some extent. Thus, by ensuring to some extent the overall bulge of the back surface and the bulge of the local back surface shape on the front edge side, it is possible to suppress a reduction in lift due to the effect of peeling (leading edge peeling) immediately downstream of the stagnation point.
Accordingly, the airfoil of the wind turbine blade has a high design lift coefficient because it satisfies the above-described conditions regarding the first dimensionless value and the second dimensionless value.
Here, in the blade length direction region where the ratio of the radial position r of the wind turbine rotor to the radius R of the wind turbine rotor is 0.1 or more and 0.4 or less, the cord length tends to be restricted for the various reasons described above. Therefore, unless the design lift coefficient is increased, the aerodynamic performance usually decreases. In other words, if the shortage of the code length with respect to the optimum code length is not compensated for by improving the design lift coefficient, the deviation from the optimum value of the product of the code length and the lift coefficient existing for each radial position will increase, resulting in high blade efficiency (output coefficient). ) Is difficult to achieve. Figure 14 is a graph showing the relation between the product of code length and the lift coefficient and the non-dimensional value in the optimum values and output the coefficient C _p. In FIG. 14, λ is a circumferential speed ratio, R is a dimensionless radius position, L / D is a lift-drag ratio, C (r) is a cord length at an arbitrary radial position, CL _design is a design lift coefficient, CL Is the lift coefficient, [C (r) × CL] _optimum is the optimum value of the product of the code length and the lift coefficient, and C _p is the output coefficient. As shown in the figure, when the deviation from the optimum value of the product of the cord length and the lift coefficient is large, the output coefficient C _p is small regardless of the magnitude of the lift-drag ratio (L / D). The lift-drag ratio (L / D) has a substantial effect on the output coefficient Cp only after the product of the cord length and the lift coefficient is sufficiently close to the optimum value. As described above, when there is a shortage of the code length with respect to the optimum code length, the optimum value of the product of the code length and the lift coefficient is compensated by the design lift coefficient instead of the lift-drag ratio (L / D). It is important to reduce the deviation from.
In this regard, the wind turbine blade having the airfoil excellent in the design lift coefficient in the blade length direction region can increase the design lift coefficient in a region near the cord direction position where the airfoil is adopted, The aerodynamic performance of the wind turbine blade can be improved.

In some embodiments, the first dimensionless value y _max / t _max is not less than 0.4 and not more than 0.46, and the second dimensionless value y _f / y _max is not less than 0.63 and not more than 0.71. It is. Further, in one embodiment, the second dimensionless value _y f _{/ y max} is 0.65 or more 0.69 or less.
If the first dimensionless value and the second dimensionless value are set in such a numerical range, the overall bulge of the back surface and the bulge of the local back surface shape on the front edge side become more appropriate, and trailing edge peeling and Lead edge separation is effectively suppressed and the design lift coefficient of the airfoil can be increased.

In some embodiments, the airfoil is a flatback airfoil with a trailing edge having a thickness.
As described above, in the region relatively close to the blade root side, the trailing edge is thickened to form a flat back airfoil, so that stall can be avoided up to a high angle of attack and the maximum lift coefficient can be improved. That is, since the airfoil in the blade length direction region in which the ratio of the radial position r is 0.1 or more and 0.4 or less is a flat back airfoil, the negative pressure generated due to the wake on the downstream side of the trailing edge. The pressure can effectively delay the peeling of the boundary layer on the back surface.

In some embodiments, the blade type of the wind turbine blade has a blade thickness ratio indicating a ratio of the maximum blade thickness t _max to the length C of the cord of 0.35 or more and 0.8 or less.

A wind turbine rotor according to some embodiments of the present invention includes:
The windmill wing,
And a hub to which the wind turbine blades are attached.

  Since the wind turbine rotor includes the wind turbine blade having the airfoil having an excellent design lift coefficient in the blade length direction region, the design lift coefficient is increased in a region in the vicinity of the cord direction position where the airfoil is adopted. Therefore, it contributes to the improvement of the aerodynamic performance of the wind turbine blade, and consequently the aerodynamic performance of the wind turbine rotor.

The diameter of the windmill rotor is 100 m or more.
As described above, according to the wind turbine rotor, since the airfoil is provided, even in a large wind turbine blade having a wind turbine rotor diameter of 100 m or more, the maximum code can be obtained without causing a significant decrease in the aerodynamic performance of the wind turbine blade. The length can be shortened. That is, a decrease in aerodynamic performance due to a reduction in the cord length of the wind turbine blade can be compensated by an increase in the design lift coefficient of the airfoil possessed by the wind turbine blade.

A wind power generator according to some embodiments of the present invention includes:
The windmill rotor,
And a generator for converting rotational energy of the windmill rotor into electric energy.

  The wind turbine generator includes a wind turbine rotor, and the wind turbine rotor has the airfoil having an excellent design lift coefficient in the blade length direction region, so that the wind turbine rotor near the cord direction position where the airfoil is adopted. The design lift coefficient can be increased in the region, which contributes to the improvement of the aerodynamic performance of the wind turbine blade, and hence the improvement of the aerodynamic performance of the wind turbine rotor.

  According to some embodiments of the present invention, it is possible to achieve a high design lift coefficient by satisfying the conditions related to the first dimensionless value and the second dimensionless value described above. The wind turbine blade having the airfoil having an excellent design lift coefficient in the blade length direction region can increase the design lift coefficient in a region in the vicinity of the cord direction position where the airfoil is adopted. The aerodynamic performance of the wing can be improved.

It is a schematic block diagram which shows the wind power generator which concerns on some embodiment. It is a schematic perspective view of the windmill blade which concerns on some embodiment. FIG. 3 is a cross-sectional view (cross section S) in the blade length direction region of the wind turbine blade shown in FIG. 2. It is sectional drawing of the flat back airfoil in other embodiment. It is a figure for demonstrating the physical meaning of a 2nd dimensionless value. It is a figure which shows the range with respect to the 1st dimensionless value and 2nd dimensionless value of an airfoil in some embodiment. It is a figure which shows the relationship of the lift coefficient with respect to an angle of attack. It is a figure which shows the relationship of the lift-drag ratio with respect to an angle of attack. It is a figure which shows code length distribution with respect to dimensionless radial position r / R. It is a graph which makes the magnitude | size of a 2nd dimensionless value the x-axis, and makes the magnitude | size of a 1st dimensionless value the y-axis. It is a figure which shows the influence which a change gives to a design lift coefficient a 1st dimensionless value. It is a figure which shows a mode that a 2nd dimensionless value is changed. It is a figure which shows the influence which the change of a 2nd dimensionless value has on a design lift coefficient. It is a graph which makes the magnitude | size of a 2nd dimensionless value the x-axis, and makes the magnitude | size of a 1st dimensionless value the y-axis. It is a figure which shows the influence which it has on the design lift coefficient at the time of changing a 2nd dimensionless value. It is a figure which shows a mode that a 1st dimensionless value is changed. It is a figure which shows the influence which the change of a 1st dimensionless value has on a design lift coefficient. It is a graph showing the relation between the product of code length and the lift coefficient and the non-dimensional value in the optimum values and output the coefficient C _p.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.

FIG. 1 is a configuration diagram illustrating a wind turbine generator 100 according to some embodiments.
A wind turbine generator 100 shown in FIG. 1 includes a wind turbine rotor 6 including at least one wind turbine blade 2 and a hub 4 to which the wind turbine blade 2 is attached, a generator 8 that converts rotational energy of the wind turbine rotor 6 into electrical energy, A nacelle 10 that supports the wind turbine rotor 6 and the generator 8 and a tower 12 that rotatably supports the nacelle 10 are provided. The exemplary wind turbine rotor 6 shown in FIG. 1 has three wind turbine blades 2. The diameter of the wind turbine rotor 6 is 100 m or more in some embodiments, and 150 m or more in one embodiment. In the present embodiment, the distance from the rotation center O of the wind turbine rotor 6 shown in FIG. 1 to the blade tip 14 of the wind turbine blade 2 is defined as the radius R of the wind turbine rotor 6, and the radial direction at an arbitrary point P of the wind turbine rotor 6. A position r (a radial distance from the rotation center O of the wind turbine rotor 6 to the point P) is assumed.

FIG. 2 is a schematic perspective view of the wind turbine blade 2 according to some embodiments. 3 is a cross-sectional view (cross section S) in the blade length direction region A of the wind turbine blade 2 shown in FIG.
As shown in FIGS. 2 and 3, the wind turbine blade 2 includes a blade tip portion 14 and a blade root portion 16 connected to the hub 4 (see FIG. 1). Further, the wind turbine blade 2 has a leading edge 18 and a trailing edge 20 from the blade root portion 16 to the blade tip portion 14. Further, the outer shape of the wind turbine blade 2 is formed by an abdominal surface (pressure side) 22 and a back surface (suction side) 24 facing the abdominal surface 22.
In the embodiment, the trailing edge 20 refers to the intersection of the back surface 24 and the abdominal surface 22 forming an acute inner angle when the airfoil 30 is not a flatback airfoil, and the airfoil 30 ′ is a flatback airfoil (see FIG. 4) is the midpoint between the rear end of the back surface 24 and the rear end of the abdominal surface 22. The leading edge 18 refers to a point having the longest distance from the trailing edge 20 defined as described above.

In some embodiments, the wind turbine blade 2 has a blade length direction region A in which the ratio (r / R) of the radial position r of the wind turbine rotor 6 to the radius R of the wind turbine rotor 6 is 0.1 or more and 0.4 or less. The airfoil 30 satisfies the conditions described later. Further, in one embodiment, the airfoil 30 has a blade thickness ratio indicating a ratio of the maximum blade thickness t _max to the cord length C of 0.35 or more and 0.8 or less.

Here, the terms used in the present embodiment will be described with reference to FIG. In FIG. 3, the direction along the code 26 of the airfoil 30 is represented by the x coordinate, and the thickness direction of the airfoil 30 is represented by the y coordinate. Further, in the figure, the x coordinate of the leading edge 18 is set to zero.
In the airfoil 30 shown in FIG. 3, a line connecting the leading edge 18 and the trailing edge 20 is a cord 26. The cord length C of the cord 26 is a length along the cord 26 from the leading edge 18 to the trailing edge 20. The maximum value of the distance between the back surface 24 and the abdominal surface 22 in the cord orthogonal direction is the maximum blade thickness _tmax, and the maximum value of the distance from the cord 26 to the back surface 24 in the cord orthogonal direction is the maximum back surface thickness _ymax . Then, the maximum back thickness y _max that is the maximum value of the distance from the cord C connecting the leading edge 18 and the trailing edge 20 to the back surface 24 with respect to the maximum blade thickness t _max that is the maximum value of the distance between the back surface 24 and the abdominal surface 22. The ratio y _max / t _max is called the first dimensionless value. The first dimensionless value is an index indicating the overall swelling of the airfoil 30 toward the back side.
Further, a cord direction position having the maximum back surface thickness y _max is defined by a distance x _max from the leading edge 18 to the cord direction position. That is, the x coordinate of the code direction position of the back surface 24 having the maximum back surface thickness y _max is x _max . Furthermore, the distance from the leading edge 18 a distance in code orthogonal direction from the code 26 in the code direction position of _{0.3x max} to the back 24, the rear front bulging amount _{y f.} The ratio y _f / y _max of the back front bulge amount y _{f to} the back maximum thickness y _max is referred to as a second dimensionless value. The second dimensionless value is an index indicating the bulge to the dorsal shapes (range up to the front edge 18~x _max) localized the front edge side of the airfoil 30.

FIG. 4 is a cross-sectional view of a flat back airfoil 30 ′ according to another embodiment. In the figure, the airfoil 30 shown in FIG. 3 is indicated by a broken line.
In other embodiments, the airfoil 30 ′ is a flat back airfoil with a trailing edge 20 having a thickness. The edge 20 of the airfoil type 30 'has a KoenAtsu _{t TE.} The cord 26 connecting the leading edge 18 and the trailing edge 20 (more precisely, the midpoint of the trailing edge surface in the blade thickness direction) has a cord length C.
The airfoil 30 ′ has the same configuration as the airfoil 30 shown in FIG. 3 except that the trailing edge 20 has a thickness, and a detailed description thereof will be omitted.

FIG. 5 is a diagram for explaining the physical meaning of the second dimensionless value. As shown in the figure, when the radius of a circle of _{x max,} intersection M between the straight line inclined 45 degrees with respect to the arc and the y-axis in the second quadrant, y coordinate of about _{0.7y max} (accurately is _{sin45 ° × y max ≒ 0.707y max} ), and, about _{0.3x max} from point N to which the arc intersects the x-axis in the x direction (more precisely, _{cos45 ° × x max ≒ 0.292x max} ) Only a distance away. Therefore, even in the case of a partial ellipse having the semi-major axis a (= x _max ) and the semi-minor axis b (= y _max ) shown on the left side of FIG. 5, the intersection point N ′ between the partial ellipse and the x axis. The y coordinate y _{f at} a position separated by 0.3x _{max in the} x direction should be about 0.7 y _max . Therefore, when the bulge is excessive on the basis of the ellipse, the second dimensionless value y _f / y _max tends to be larger than 0.7. Conversely, when the bulge is excessively small with respect to the ellipse, the second dimensionless value y _f / y _max tends to be smaller than 0.7. As described above, if the second dimensionless value y _f / y _max is used as an index for evaluating the shape of the back surface 24 on the front edge side of the airfoil 30, 30 ′, the locality on the front edge side of the airfoil 30, 30 ′ is used. Can represent a bulge to the back side of the shape (ranging from the leading edge 18 to x _max ).

FIG. 6 is a diagram illustrating ranges for the first dimensionless value and the second dimensionless value of the airfoils 30, 30 ′ in some embodiments.
The wind turbine blade 2 according to some embodiments has an airfoil 30 that satisfies all of the following conditions regarding the first dimensionless value and the second dimensionless value in the blade length direction region A of the windmill blade 2 shown in FIG. 30 '.

In some embodiments, the airfoil 30, 30 ′ has a first dimensionless value y _max / t _max of 0.36 or greater and 0.46 or less, and a second dimensionless value y _f / y _max of It is 0.62 or more and 0.76 or less. That is, the coordinates represented by the first dimensionless value and the second dimensionless value of the airfoil 30, 30 ′ are included in the first range shown in FIG.
According to the knowledge of the present inventors, the airfoil 30, 30 ′ that satisfies the conditions regarding the first dimensionless value and the second dimensionless value has a high design lift coefficient CL _design .

Here, the design lift coefficient CL _design is a lift coefficient corresponding to the optimum angle of attack at which the maximum lift-drag ratio is realized. This will be described with reference to FIGS.
7 and 8 are diagrams for explaining the design lift coefficient CL _design . FIG. 7 shows the relationship of the lift coefficient to the angle of attack, and FIG. 8 shows the relationship of the lift-drag ratio to the angle of attack. .
The design lift coefficient CL _design is a lift coefficient CL corresponding to the angle of attack (the optimum angle of attack shown in FIG. 8) at which the lift-drag ratio L / D is maximum in the relationship between the angle of attack and the lift coefficient shown in FIG. is there. In the case of a typical variable speed windmill, since the optimum angle of attack is operated during variable speed operation, the design lift coefficient CL _design indicates the performance of the wind power generator 100 during variable speed operation. It depends on you.
In a typical variable speed wind turbine, it is desired that the lift can be maintained without stalling to a high angle of attack in a wind speed region above the rated wind speed at which the angle of attack is greater than the optimum angle of attack. The maximum lift coefficient CL _max shown in FIG. 7 affects the performance of the wind turbine generator in such a high wind speed region.

'In, set the ratio of the rear maximum thickness _{y max} for the maximum blade thickness _{t max} (the first dimensionless value) to 0.46 airfoil 30, 30' wing 30, 30 overall to the dorsal And the ratio (second dimensionless value) of the back front bulge amount y _{f to} the back maximum thickness y _max is set to 0.76 or less to locally reduce the airfoil 30, 30 ′ on the front edge 18 side. such that suppresses expansion of the (previous range to the edge ~x _max) dorsal shape. Thus, the overall bulge of the back surface 24 and the local back surface bulge on the leading edge 18 side are suppressed, and the boundary layer along the back surface 24 (the blade surface normal direction in the region where the flow velocity near the blade surface is slow) Development) is delayed, and peeling (rear edge peeling) from the back surface 24 on the rear edge 20 side is suppressed, and lift can be improved. Thus, the airfoils 30, 30 ′ can achieve a high design lift coefficient CL _design and a maximum lift coefficient CL _max .
Furthermore, airfoil 30, 30 ', set the ratio of the rear maximum thickness _{y max} for the maximum blade thickness _{t max} (the first dimensionless value) to 0.36 or more airfoil 30, 30' to the dorsal While ensuring a certain amount of overall bulge, the ratio of the back front bulge amount y _{f to} the maximum back surface thickness y _max (second dimensionless value) is set to 0.62 or more to set the leading edge 18 of the airfoil 30, 30 ′. The bulge to the back side of the local shape (in the range from the leading edge to x _max ) is ensured to some extent. In this way, by suppressing the overall bulge of the back surface 24 and the local bulge of the local back shape on the front edge 18 side to some extent, the reduction in lift due to the effect of peeling (leading edge peeling) immediately downstream of the stagnation point is suppressed. it can.
Thus, since the airfoil 30, 30 ′ of the wind turbine blade 2 satisfies the above-described conditions regarding the first dimensionless value and the second dimensionless value, it has a high design lift coefficient CL _design and a maximum lift coefficient CL _max .

By the way, in the blade length direction region A in which the ratio of the radial position r of the wind turbine rotor 6 to the radius R of the wind turbine rotor 6 is 0.1 or more and 0.4 or less, the cord length tends to be restricted. This will be described with reference to FIG.
FIG. 9 is a diagram showing a code length distribution with respect to a dimensionless radius position A (= r / R). As shown in the figure, a typical wind turbine blade has a maximum cord length C inside or in the vicinity of a blade length direction region A of 0.1 ≦ r / R ≦ 0.4. Assuming that the design lift coefficient CL _design is constant, in order to achieve optimum aerodynamic performance, the dimensionless radial position r / R and the code length C have an inversely proportional correlation as shown by the broken line in FIG. It is necessary to have. In a typical wind turbine blade, the code length C is insufficient with respect to the optimum code length distribution indicated by the broken line in FIG. 9 in the region near the maximum code length position. In order to solve various problems associated with the increase in wind turbine blade length (increased weight of the wind turbine blade, decrease in manufacturability and transportability of the wind turbine blade, decrease in operability of the wind turbine generator, etc.) This is because restrictions are imposed on the system.
Thus, in the blade length direction region where the ratio of the radial position r of the wind turbine rotor 6 to the radius R of the wind turbine rotor 6 is 0.1 or more and 0.4 or less, the cord length C tends to be restricted. As a result, the code length C tends to be insufficient with respect to the optimal code length distribution.

In this respect, the wind turbine blade 2 according to the present embodiment has the airfoil 30, 30 ′ having an excellent design lift coefficient CL _design as described above in the blade length direction region of 0.1 ≦ r / R ≦ 0.4. Therefore, it is possible to suppress a decrease in aerodynamic performance due to the shortage of the code length C with respect to the optimum code length distribution.

In some embodiments, the airfoil 30, 30 ′ has a first dimensionless value y _max / t _max of 0.4 to 0.46 and a second dimensionless value y _f / y _max of 0. It is 63 or more and 0.71 or less. That is, the coordinates represented by the first dimensionless value and the second dimensionless value of the airfoil 30, 30 ′ are included in the second range shown in FIG.
Further, in one embodiment, airfoil 30, 30 'is a second dimensionless value _y f _{/ y max} is 0.65 or more 0.69 or less. That is, the coordinates represented by the second dimensionless value of the airfoil 30, 30 ′ are included in the third range shown in FIG.
If the first dimensionless value and the second dimensionless value are set in these numerical ranges, the overall bulge of the back surface 24 and the bulge of the local back surface shape on the front edge 18 side become more appropriate, and the trailing edge Peeling and leading edge peeling are effectively suppressed, and the design lift coefficient CL _design of the airfoil 30, 30 ′ can be increased.

  Here, regarding the progress of the discussion until the present inventors have found that the above-described conditions of the first dimensionless value and the second dimensionless value contribute to the improvement of the design lift coefficient of the airfoil 30, 30 ′, This will be described with reference to FIGS.

FIG. 10A is a graph in which the magnitude of the second dimensionless value is the x axis and the magnitude of the first dimensionless value is the y axis. In the figure, a point 40 indicates an airfoil with a blade thickness ratio of 40% in a typical wind turbine blade (hereinafter referred to as a reference airfoil). As shown in FIG. 10A, FIG. 10B shows the influence on the design lift coefficient when the first dimensionless value is changed in a direction to make it smaller than the reference airfoil 40. As shown in FIG. 10B, the first dimensionless value range in which the design lift coefficient CL _design is higher than that of the reference airfoil 40 was found. In particular, in the range where the first dimensionless value is 0.38 ≦ y _max / t _max ≦ 0.47, it has become clear that the design lift coefficient CL _design is significantly improved as compared with the reference airfoil 40. Furthermore, it has been clarified that the design lift coefficient CL _design reaches the maximum value within the range where the first dimensionless value is 0.40 ≦ y _max / t _max ≦ 0.46 under this calculation condition.
Subsequently, in the first dimensionless value range (0.40 ≦ y _f / y _max ≦ 0.46), the second dimensionless value is changed in a direction to be smaller than the reference airfoil 40. This is shown in FIG. 11A. FIG. 11B is a diagram illustrating the influence of the change in the second dimensionless value on the design lift coefficient. As shown in the figure, the range of the second dimensionless value where the design lift coefficient CL _design is increased was found. In particular, in the range where the second dimensionless value is 0.63 ≦ y _f / y _max ≦ 0.71, the design lift coefficient CL _design is remarkably improved as compared with the reference airfoil 40. Furthermore, it has been clarified that the design lift coefficient CL _design reaches the maximum value within the range where the second dimensionless value is 0.65 ≦ y _f / y _max ≦ 0.69 under this calculation condition.

On the other hand, FIG. 12A is a graph in which the magnitude of the second dimensionless value is taken as the x axis and the magnitude of the first dimensionless value is taken as the y axis. In the figure, a point 40 represents the above-described reference airfoil. As shown in FIG. 12A, FIG. 12B shows the influence on the design lift coefficient when the second dimensionless value is changed in a direction to make it smaller than the reference airfoil 40. As shown in FIG. 12B, under this calculation condition, it was not possible to find a clear range of the second dimensionless value in which the _design lift coefficient CL _design was improved.
Therefore, it has been shown that the first dimensionless value is changed in a direction to make it smaller than the reference airfoil 40 over a wide range of the second dimensionless value (0.62 ≦ y _f / y _max ≦ 0.75). Is FIG. 13A. FIG. 13B is a diagram illustrating the influence of the change in the first dimensionless value on the design lift coefficient. As shown in the figure, the first dimensionless value range in which the design lift coefficient CL _design is increased was found. In particular, the design lift coefficient CL _design is significantly improved as compared with the reference airfoil 40 in the range where the first dimensionless value is 0.38 ≦ y _max / t _max ≦ 0.46.

  From the above consideration process by the present inventors, it has become clear that the above-described conditions of the first dimensionless value and the second dimensionless value in the present embodiment can contribute to an increase in the design lift coefficient.

As described above, according to the above-described embodiment, a high design lift coefficient is obtained when the airfoil 30, 30 ′ of the wind turbine blade 2 satisfies the above-described conditions regarding the first dimensionless value and the second dimensionless value. CL _design and maximum lift coefficient CL _max can be achieved. In the blade length direction region A, the wind turbine blade 2 having the airfoil 30, 30 ′ having excellent design lift coefficient CL _design and maximum lift coefficient CL _max is a code in which the airfoil 30, 30 ′ is adopted. The design lift coefficient CL _design and the maximum lift coefficient CL _max can be increased in the region near the directional position, and the aerodynamic performance of the wind turbine blade 2 can be improved.
Further, in the region relatively close to the blade root portion 16 side, if the trailing edge 20 is made thick so as to be a flat-back blade type (see FIG. 4), stall can be avoided up to a high angle of attack, and the maximum lift coefficient CL _max can be increased. Can be improved. That is, since the airfoil 30 ′ in the blade length direction region in which the ratio of the radial position r is 0.1 or more and 0.4 or less is a flat back airfoil, it is caused by the wake on the downstream side of the trailing edge 20. The generated negative pressure can effectively delay the separation of the boundary layer on the back surface 24.

  As mentioned above, although embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to this, In the range which does not deviate from the summary of this invention, various improvement and deformation | transformation may be performed.

2 wind turbine blade 4 hub 6 wind turbine rotor 8 generator 10 nacelle 12 tower 14 blade tip 16 blade root 18 leading edge 20 trailing edge 22 abdominal surface 24 back surface 30, 30 'airfoil 40 reference airfoil 100 wind power generator A blade length direction Region C Code length CL _design Design lift coefficient CL _max Maximum lift coefficient t _max Maximum blade thickness y _f Backward bulge amount y _max Maximum surface thickness y _max / t _max First dimensionless value y _f / y _max Second dimensionless value

Claims (6)

A wind turbine blade for a wind turbine rotor having a back surface and an abdominal surface facing each other,
The wind turbine blade has a maximum cord length in a blade length direction region of the wind turbine blade where a ratio of a radial position r of the wind turbine rotor to a radius R of the wind turbine rotor is 0.1 or more and 0.4 or less. In
The first dimensionless value y _max represented by the ratio of the maximum back surface thickness y _max that is the maximum value of the distance from the code to the maximum blade thickness t _max that is the maximum value of the distance between the back surface and the abdominal surface. / _{t max} is 0.36 or more 0.46 or less, and, second dimensionless value _y f _{/ y max} represented by the ratio of the back front bulging amount _{y f} with respect to the rear maximum thickness _{y max} 0.62 Is equal to or greater than 0.76 (however, the back front bulge amount y _f is defined as a distance x _max from the front edge to the cord direction position of the cord direction position of the back surface having the maximum back surface thickness y _max. The distance from the front edge is the distance from the cord to the back surface at a cord direction position of 0.3x _max )
Having an airfoil ,
The wind turbine rotor has a diameter of 100 m or more;
A wind turbine blade for a wind turbine rotor, wherein the blade thickness ratio of the airfoil is 0.35 or more and 0.8 or less . The first dimensionless value y _max / t _max is not less than 0.4 and not more than 0.46;
2. The wind turbine blade for a wind turbine rotor according to claim 1, wherein the second dimensionless value y _f / y _max is 0.63 or more and 0.71 or less. 3. The wind turbine blade for a wind turbine rotor according to claim 2, wherein the second dimensionless value y _f / y _max is 0.65 or more and 0.69 or less.   4. The wind turbine blade for a wind turbine rotor according to claim 1, wherein the airfoil is a flat-back airfoil with a trailing edge having a thickness. 5. The wind turbine blade according to any one of claims 1 to 4 ,
And a hub to which the wind turbine blades are attached. A wind turbine rotor according to claim 5 ;
And a generator for converting rotational energy of the windmill rotor into electric energy.

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